Scientists found a longevity diet that helped mice eat more and lose fat
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- USC researchers found that a low-protein, methionine-supplemented Mediterranean-style diet increased healthspan, reduced body fat, and lowered frailty in 20-month-old mice compared with standard, Western, and ketogenic diets, per a study published in Cell Metabolism.
- Mice on the longevity diet ate more food and consumed as many calories as other groups yet still lost body fat while maintaining lean muscle mass, with benefits appearing only when methionine levels stayed low but sufficient.
- Analysis of more than 200,000 people by researchers from USC, the University of Toronto, and Harvard linked the highest animal-protein intake to higher obesity rates and twice the risk of Type 2 diabetes versus those eating little or no animal protein.
- Senior author Valter Longo said the findings challenge "the dogma that calorie reduction is necessary to lose weight," cautioning that too little methionine caused frailty while too much abolished the diet's benefits.
- First author Maura Fanti said modulating just one amino acid produced "dramatic metabolic changes," suggesting amino acid composition — not total protein quantity — may be the real metabolic lever.
- The research team is planning controlled clinical trials in humans, noting LDMM-fed mice also showed elevated GLP-1 and other metabolic hormones tied to cardiometabolic health.
- Study disclosures: Valter Longo holds equity in L-Nutra, a company that develops medical foods, and has filed patents related to fasting-mimicking diets through USC, which has licensed related intellectual property to L-Nutra.
Why it matters: Mouse results cut against the calorie-reduction orthodoxy by producing fat loss on higher intake, but the consumer-facing payoff — confirmed human benefit — still hinges on clinical trials the team plans next, while senior author Longo's equity stake in medical-food maker L-Nutra signals a commercial pipeline behind the research.
